Simple Vision Test Predicts IQ

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A simple visual test is surprisingly accurate at predicting IQ,
according to new research.

The study, published today (May 23) in the journal Current
Biology, found that people's ability to efficiently filter out
visual information in the background and focus on the foreground
is strongly linked to IQ. The findings could help scientists
identify the brain processes responsible for
intelligence.

That doesn't mean snappy, efficient
visual processing leads to smarts, said study co-author Duje
Tadin, a neuroscientist at the University of Rochester in New
York. Instead, common brain processes may underlie both
intelligence and efficient visual processing.

IQ hunting

Since the 1800s, the forefathers of IQ
testing, including Sir Francis Galton (who also pioneered the
science of fingerprinting ), suspected that highly intelligent
people also have supersensory discrimination.

But studies in the subsequent decades have found only a modest
connection between IQ-test scores and people’s ability to quickly
or accurately spot motion in images.

Tadin and his colleagues were studying a separate question on
visual perception in 12 participants when they found something
striking: IQ seemed to be correlated strongly with performance on
a visual task.

The test asked users to spot the direction of motion on a series
of black-and-white stripes on a screen. Sometimes, the lines
formed inside a small central circle, and other times, they were
large stripes that took up the entire screen. Participants also
completed a short IQ test. [Watch Video of Motion and Test Your
Smarts]

The team noticed that people with
higher IQs were good at spotting motion in the small circles,
but terrible at detecting motion in the larger black-and-white
stripes.

Because they had looked at so few people, Tadin and his
colleagues wondered if their results were a fluke. They repeated
the experiment with 53 people, who also took a full IQ test.

The ability to visually filter the motion strongly predicted IQ —
in fact, motion suppression (the ability to focus on the action
and ignore background movements) was as predictive of total IQ as
individual subsections of the IQ test itself.

Relevant information

As people walk, the background scenery is always changing, so
efficient brains may be better at filtering out this irrelevant
visual information. And that efficiency could be operating across
a wide range of tasks, Tadin said.

The findings reshape the conventional view that quick thinking
leads to smarts.

"Speedy processing does matter, but it's only half the story.
It's how you filter out things that are less relevant and focus
your speedy resources on what is important," Tadin said.

Big variation

The study reveals new insights into brain efficiency and smarts,
said Kevin McGrew, director of the Institute for Applied
Psychometrics and owner of www.themindhub.com.

Even though the link between IQ and visual filtering was very
strong, IQ tests won't be replaced by motion tracking anytime
soon, said McGrew, who was not involved in the study.

"Their task accounts for or explains about 50 percent of the IQ
scores," McGrew told LiveScience. "That is impressive in
psychology, but it still means there is 50 percent of the
scores that they're not explaining."